The field of this invention relates to manufacturing equipment and methods for making and reinforcing hoses and more specifically reinforcing hoses with a circular weft knit to resist internal pressures within the hose.
The present state of the art of knitting comprises many different kinds of knitting machines. They are broadly classified as one of two types “Flat Knitting Machines” and “Circular Knitting Machines”. Each type of knitting machine has many variations for various types of textiles. The Flat Knitting Machines generally have a straight knitting bar that knits one or more yarns into a flat textile sheet. The Circular Knitting Machines have a circular knitting head and knit a tube shaped textile that can be cut into a flat sheet if desired. Both the Flat and Circular knitting machines are designed for many different knit patterns which can be classified as either a Warp Knit (yarn runs longitudinally with the fabric's length) or Weft Knit (yarn runs transverse to the fabric's length). Circular weft knitting machines are use for making socks, undershirts, and other tubular fabric including reinforcement and covers for hoses. Circular weft knitting machines are also used for general fabric production because of the limited number of yarn spools needed to begin production. Weft knitting machines can produce fabric with as little as one yarn strand, but may use many dozens of yarn strands. Warp knitting machines, on the other hand, generally have many thousands of individual yarn strands that run lengthwise along the fabric and are all knitted together to form a fabric.
The first circular weft knitting machines where single yarn devices, where the yarn would be pulled from a single spool and moved around the circular knitting head to allow it to engage all the knitting needles and form the tubular knitted product. Neither the knitting head, produced fabric nor the yarn packages rotated around the axis of the knitting machine. However, to increase speed, additional yarn strands were soon used, which made it necessary to do one of two things. Either the yarn packages needed to rotate around the knitting head to feed yarn to the knitting needles (so the yarns did not tangle), or the knitting head and produced fabric must rotate together to allow the yarn packages to remain on stationary racks. The disclosed invention fits in this last category, where the yarn packages or spools are stationary, and the knitting head and knitting needles rotate to produce a rotating tube shaped fabric.
Prior Art circular knitting machines for knitting reinforcement on hoses appears to be confined to knitting machines for reinforcing non-rotating hoses. In FIG. 1, we see a typical prior art circular knitting machine, U.S. Pat. No. 6,834,517 for a “Yarn Feeding System” issued to Sheehy, Jr. FIG. 1 of the specifications show a yarn feeding system for a typical circular weft hose knitting machine. Knitting machine 10 provides a rotatable deck 15 which rotates multiple yarn packages 16 around knitting head 20 to feed yarn 18 to knitting needles 22. Knitting head 20, hose 20 and needles 22 do not rotate to knit reinforcement P on hose 12 and thus knitting head 20 matches speed with hose 12. The rate at which hose 12 is pulled through knitting head 20 determines the rate at which knitting machine 10 can provide a tightly knitted cover for hose 12 and produce reinforced hose 14. In operation, roller 13 pulls hose 12 through knitting head 20 from the top. Yarn packages 16 rotate at high speed around knitting head 20, while feeder head assembly 30 draw in yarn and direct it to knitting needles 22. Through weft knitting action a circular knit is produced around hose 12 and is tightened around hose 12 to provide reinforcement. In this hose wrapping design by Sheehy and other similar prior art hose wrapping circular weft knitting machines a non-rotating hose is pulled through the knitting machine. Thus, neither are the knitting head nor knitting needles are rotating as the hose reinforcement is knitted over the hose. However, to use more than one yarn spool requires that the yarn spools rotate around the knitting head, at high speed, to feed yarn to the knitting needles and producing the weft knit. This greatly increases the complexity of the circular knitting machine and adds cost. Nearly eighty percent of the equipment weight for these machines is associated with the need to rotate the yarn spools deck 15 at high speed. The Applicant's circular knitting machine eliminates this rotatable deck and with it much of the cost of the machinery.
To get around having to rotate the yarn spools at high speed, some systems like the circular knitting machine 100 seen in U.S. Pat. No. 6,381,993 B1 issued to Hermann allows many stationary yarn spools to be used by rotating his Knitting Cylinder and Dial (circular knitting head). This creates the problem when making a knitted tube, which is the problem of collecting a rotating knitted article. Thus to collect the knitted fabric on the take-up roller (see roller 135 in Hermann) the roller must rotate with the knitting cylinder (see knitting cylinder 111 in Hermann). Similar, but larger diameter knitting machines like U.S. Pat. No. 5,575,162 issued to Gray are also used rotating collection mandrel 22 to collecting knitted fabric on a roller or spool. Gray's device ones like it rotate much too slowly because of their size and would not be appropriate for the purposes of reinforcing a hose, and like Hermann, still has the problem in how to rotate the hose with their system (hose rotation on both sides of a prior art circular knitting machine). The Applicant's circular knitting machine does not need a rotating take-up roller and assembly like Gray shows, nor does it need a rotating deck of yarn spools like Sheehy shows. Both of these types of systems, found in the prior art, are not needed by the Applicant's knitting machine, because the reinforcement go directly on a rotating hose that is being manufactured. This elimination of the weight associated with turning a fabric take-up roller, and elimination of a large rotating deck, greatly reduces the cost of the Applicant's system compared to the prior art. For knitting reinforcement around a hose, all prior art hose knitting and wrapping machines that were found required the hose not to rotate and required a large rotating deck of yarn spools. Thus, The applicant's device eliminates a very costly and dangerous component of prior art hose reinforcement machinery.